The invention relates generally to movable windscreen apparatus mounted on motorcycles for moving a windscreen up or down in accordance with voluntary operation of a rider or vehicle speed, and in particular to a windscreen apparatus for motorcycles, in which even when trouble occurs in a drive mechanism of the apparatus during motorcycle riding, it does not cause an awful sensation to the rider.
When riding a vehicle such as a motorcycle which has no cabin, the rider is continuously subjected to wind pressure (air resistance) from the traveling direction. A proportional relationship exists between the vehicle speed and the wind pressure from the traveling direction. As the vehicle speed is increased, the body of the rider receives a stronger force in a backward direction from the wind pressure. In order to maintain his or her riding posture, the rider is continuously required to exert a large force to hold the handlebar. After a long distance riding at a high speed, he or she feels a strong exhaustion. Further, the wind that the rider receives during riding affects the body temperature of the rider, and thus his or her exhaustion is increased. In order to reduce the exhaustion of the rider due to such wind, many middle or large sized motorcycles suitable for long-distance traveling, which are generally called “tourers,” are equipped with a windscreen as a standard accessory.
The windscreen effectively prevents the rider from being subjected to direct wind from the front. However, when a vehicle equipped with too large a windscreen runs at a high speed, a problem arises in that the vehicle body suffers a large air resistance resulting in a decrease in fuel efficiency. Moreover, as the vehicle speed increases, the rider tends to lower his or her riding posture by forwardly inclining his or her upper body on the motorcycle. However the rider makes his or her riding posture lower by forwardly inclining his or her upper body, if the windscreen is maintained without changing its original height, the windscreen still receives a large wind resulting in a decrease of the fuel efficiency of the vehicle. Furthermore, body shapes of riders of motorcycles are widely different from each other. Therefore, the height of the windscreen is desired to be adjustable in accordance with the size of the rider.
Conventionally, a movable windscreen apparatus disclosed in patent document 1 (Japanese Laid-Open Patent Publication Serial No. 2000-159172) is known as a solution to the above problems. The movable windscreen apparatus disclosed in patent document 1 includes a guide rail, a carrier plate that is slidably disposed on the guide rail, and a windscreen mounted at a lower end of the carrier plate. The movable windscreen apparatus is arranged so that the windscreen is connected to the vehicle body via links at the lower ends thereof so as to drive and slide the carrier plate by means of a driving force of a motor transmitted via cables.
In such structure, when the motor is activated as the drive source, the cables are wound up to raise the carrier plate. The carrier plate pushes up the inclined windscreen from the bottom end thereof. Since the windscreen is supported at right and left ends thereof by the links, one end of which is connected to the vehicle body, the windscreen is held in its raised position. That is, the movable windscreen apparatus disclosed in patent document 1 is an excellent technology in the following point. That is, not only is the windscreen slidable, but also, while being stored, the windscreen can be inclined to thereby reduce the wind pressure that the windscreen receives.
However, the movable windscreen apparatus disclosed in patent document 1 has a structure in which the cables transmit the driving force of the motor to the carrier plate. Therefore, one of the cables is naturally connected to an upper area of the carrier plate, and another cable is connected to the lower area thereof. By pulling or releasing the cables under tension, the carrier plate is raised and lowered. In such structure, even when the cable connected to the upper area of the carrier plate is accidentally broken during running, the carrier plate is simply lowered and the windscreen is inclined. Therefore, it seems that the structure has no particular problem.
However, when the cable connected to the lower area of the carrier plate is accidentally broken during running, the strained upper cable causes the carrier plate to rise abruptly; and accordingly the windscreen, which is under the wind pressure from its running direction, pops up toward the face of the rider. Even if the windscreen does not hit directly on the rider's face, there is a possibility that the rider is astonished and loses his or her balance leading to a miss-operation of the handlebar. In the case of riders of motorcycles, a small miss-operation of the handlebar may cause the vehicle to fall, with the fall of the vehicle leading directly to an injury to the rider. Particularly in the case of a rider who has already run a long distance on a motorcycle, his or her concentration power is reduced due to fatigue. Therefore, it is strongly required that, even when a mechanical failure occurs on an accessory or instrument, it should not cause the rider to be frightened nor give him or her an awful sensation.
Further, in the movable windscreen apparatus disclosed in patent document 1, due to its movable structure, the windscreen has to be connected with the carrier plate and the links at a point respectively. Therefore, it is doubtful in the assembly strength of the apparatus. Especially, not only that the windscreen of the motorcycle receives an extremely large wind pressure during its running at a high speed but also, under such situation, a bird or the like may actually hit thereon. Therefore, not only during running at a high speed but also even when something strikes the windscreen, there must not happen such a case that the windscreen falls off during running.
Furthermore, in the movable windscreen apparatus disclosed in patent document 1, due to its structure one end of the link has to be connected to the vehicle body. Therefore, when mounting the windscreen apparatus in accordance with patent document 1 to a vehicle body, a base for connecting the link has to be provided on the vehicle body also. Therefore, it is difficult to assemble the movable windscreen apparatus disclosed in patent document 1 to the vehicle body afterward. Therefore, the apparatus has to be exclusively designed for each model of the vehicle. That is, the movable windscreen apparatus disclosed in patent document 1 has a problem that the product is not easily generalized.